When the second PCIe slot is at the bottom of the motherboard

[Sophodot]

I've been comparing B850 and B860 ATX motherboards and one of the features I was looking for was a second PCIe x16 running at x4 where I could install another GPU. This is found on plenty of boards, such as Asrock B850/B860 Pro RS, MSI B850/B860 TOMAHAWK and ASUS ROG STRIX B850-A/B860-A. However, that second slot is often at the lowest position on the motherboard. I didn't realize this could be a problem until I actually looked at my PC.

In a typical case right below the motherboard is the PSU and even if it wasn't, there are only 7 PCIe brackets, so an average 2-slot GPU wouldn't fit in that place anyway. Also some of the motherboard connectors could be obstructed. There isn't any technical reason why the secondary PCIe can't be placed somewhere in the middle. Doing that might cover one or more M.2s by a graphics card and increase temperatures, but at least it's more likely to fit without a riser.

If multi-GPU is so dead it's never worth considering, what expansion cards are board designers expecting people to use in their non-primary slots? Are they trying to prevent inexperienced builders from accidentally installing their GPU in the inappropriate slot? Is there a logic behind this or do they just not care because few people will ever use a second PCIe card?

 

[QckSilver]

I don't get why exactly is that an issue.

As you mentioned, Multi-GPU is dead - for gaming at least. My GPU is a tripple slot sitting at the top PCI-e x16 and i have a sound card at the bottom PCI-e. There are many connectors in that area but none are bent or having issues with space. The bottom PCI-e is often not really populated with GPUs no longer, and just as the PCI era, it's kept in mind that stuff like sound cards, capture cards or NVME adapters go in that place instead, so there's absolutely no problem.

 

[_JP_]

If multi-GPU is so dead it's never worth considering, what expansion cards are board designers expecting people to use in their non-primary slots?

10Gbps Ethernet, 802.11ax, M.2 adapter, U.2 adapter, sound card, HDMI capture card, Thunderbolt adapter, etc.

This to say, so as long as you're not lane starved by the slot considering the card you want, there are plenty of options.

DX12 mGPU isn't dead, devs just didn't adopt it because it shifted all of the work of making it actually work to them and as we know, games are about profit these days instead of being technologically advanced.

 

[Ruru]

I have a M.2 -> PCIe adapter on the most bottom slot. Still fast enough for a game drive even though it's a PCIe 2.0 slot.

 

[qxp]

It's a problem for servers as well - the manufacturers are intentionally making GPUs too big so you can't fit more than one and have to shell out for pricier H200.

 

[PLAfiller]

I've been comparing B850 and B860 ATX motherboards and one of the features I was looking for was a second PCIe x16 running at x4 where I could install another GPU. This is found on plenty of boards, such as Asrock B850/B860 Pro RS, MSI B850/B860 TOMAHAWK and ASUS ROG STRIX B850-A/B860-A. However, that second slot is often at the lowest position on the motherboard. I didn't realize this could be a problem until I actually looked at my PC.

In a typical case right below the motherboard is the PSU and even if it wasn't, there are only 7 PCIe brackets, so an average 2-slot GPU wouldn't fit in that place anyway. Also some of the motherboard connectors could be obstructed. There isn't any technical reason why the secondary PCIe can't be placed somewhere in the middle. Doing that might cover one or more M.2s by a graphics card and increase temperatures, but at least it's more likely to fit without a riser.

If multi-GPU is so dead it's never worth considering, what expansion cards are board designers expecting people to use in their non-primary slots? Are they trying to prevent inexperienced builders from accidentally installing their GPU in the inappropriate slot? Is there a logic behind this or do they just not care because few people will ever use a second PCIe card?

There are pc cases that take this into account...sort of. Like mATX cases with 5 slots instead of 4. Or ATX cases with 8 slots instead of seven. This will limit you to using a 2-slot design on the most bottom slot, but at least is an option. So you could go for what you want, but perhaps consider a different case?

 

[Assimilator]

I've been comparing B850 and B860 ATX motherboards and one of the features I was looking for was a second PCIe x16 running at x4 where I could install another GPU. This is found on plenty of boards, such as Asrock B850/B860 Pro RS, MSI B850/B860 TOMAHAWK and ASUS ROG STRIX B850-A/B860-A. However, that second slot is often at the lowest position on the motherboard. I didn't realize this could be a problem until I actually looked at my PC.

In a typical case right below the motherboard is the PSU and even if it wasn't, there are only 7 PCIe brackets, so an average 2-slot GPU wouldn't fit in that place anyway. Also some of the motherboard connectors could be obstructed. There isn't any technical reason why the secondary PCIe can't be placed somewhere in the middle. Doing that might cover one or more M.2s by a graphics card and increase temperatures, but at least it's more likely to fit without a riser.

If multi-GPU is so dead it's never worth considering, what expansion cards are board designers expecting people to use in their non-primary slots? Are they trying to prevent inexperienced builders from accidentally installing their GPU in the inappropriate slot? Is there a logic behind this or do they just not care because few people will ever use a second PCIe card?

The only reason they offer that 2nd PCIe slot is as a box-ticking exercise. My suggestion would be to consider a PCIe riser cable, the x4 ones aren't too expensive.

 

[Bill_Bright]

In a typical case right below the motherboard is the PSU

I don't know what you are calling a "typical case". Most "mid" tower cases leave plenty of room, even with standard size ATX motherboards.

I think you need to be more specific. If this is a case you already own, then please list the hardware you have. You can fill out your TPU System Specs.

If you have not bought a new case yet, shop around.